IOWA ACADEMY OF SCIENCES. 
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the seventh day. On the eighth day it appeared rather 
muddy; it coagulated milk ’with a blue liquid on top. The 
curd was dissolved slowly. In twenty-five days the pro- 
cess was completed excepting a small portion in bottom of 
the flask. 
Dunha7n^s peptone solution . — No color produced. The 
medium became cloudy, which was by no means character- 
istic. It failed to grow in Dunham’s rosalic acid solution. 
B. pyocyaneus is another familiar organism which pro- 
duces blue color. Dr. M. Nicolle and Dr. Zia Bey record 
observations, made from four samples, relative to the pig- 
mentary functions of this organism. On one medium 
the composition of which is not given, the pigment was 
greenish and non-fluorescent, on the other four media 
green and fluorescent. The authors also found that the 
presence of phosphates in the medium, while favoring the 
formation of fluorescent green pigment was not an indis- 
pensable condition thereof. While the greenish pigment 
and the rusty-brown pigment (resulting from the oxidation 
of the fluorescent green) passed readily through the 
Chamberland filter, the fluorescent green pigment was 
entirely held back. 
This slightly disagrees with Herr K. Wolf, who says: 
‘^The green pigment of fluorescing bacteria occurs only 
when the conditions of nutrition are extremely favorable 
to bacteria. The production of pigment is of necessity 
associated with three factors, phosphoric acid salts, easily 
decomposable ammonia compounds, and free oxygen. If 
one of these factors be absent or insufficient, pigment does 
not appear. During the aerobic growth of fluorescent 
bacteria, oxygen is copiously absorbed and carbonic acid 
gas is given off. Under similar conditions fluorescing 
bacteria produce a very considerable quantity of 
ammonia.” 
Along the same lines Doctor Keferstein describes a coccus 
which imparts a reddish hue to milk. “The color first 
appears five or six days after inoculation, and attains its 
maximum degree in about two weeks. The formation of 
